package com.jack.leetcode.eachProblem06;

public class 正则表达式匹配 {

    public static void main(String[] args) {
        System.out.println(isMatch("aa", "a*"));
        System.out.println(isMatch("aab", "c*a*b"));
        System.out.println(isMatch("mississippi", "mis*is*p*."));
        System.out.println(isMatch("mississippi", "mis*is*ip*."));
    }

    public static boolean isMatch(String s, String p) {
        s = " " + s;
        p = " " + p;
        int m = s.length();
        int n = p.length();
        boolean[][] dp = new boolean[m + 1][n + 1];
        dp[0][0] = true;

        for (int i = 1; i <= m; i++) {
            for (int j = 1; j <= n; j++) {
                if (s.charAt(i - 1) == p.charAt(j - 1) || p.charAt(j - 1) == '.') {
                    dp[i][j] = dp[i - 1][j - 1];
                } else {
                    if (p.charAt(j - 1) == '*') {
                        if (s.charAt(i - 1) != p.charAt(j - 2) && p.charAt(j - 2) != '.') {
                            dp[i][j] = dp[i][j - 2];
                        } else {
                            dp[i][j] = dp[i][j - 1] || dp[i][j - 2] || dp[i - 1][j];
                        }
                    }
                }
            }
        }
        return dp[m][n];
    }
}
